Lamp and holder assembly



Nov. 13, 1962 LAMP AND HOLDER ASSEMBLY Filed Dec. 19, 1960 CARL L.PETERS0NI ATT RNEY c. L. PETERSON I 3,064,157-

United States Patent 3,064,157 LAMP AND HOLDER ASSEMBLY Carl L. Peterson, Manchester, N.H., assignor to Sylvania Electric Products Inc., a corporation of Delaware Filed Dec. 19, 1960, er. No. 76,587 5 Claims. (Cl. 313-318) This invention relates to electric discharge lamps and lamp holders. More specifically, the invention relates to the combination of lamps and lamp holders which are suitable for use in areas where large shock and vibrational forces will tend to inordinately increase lamp outage.

Electric discharge lamps have replaced incandescent lamps in many fields due to the increased light emission and long lamp life. In addition to uses such as street and highway lighting, the electric discharge lamps have found application in such fields as factory illumination and the lighting of missile bases. Each of these installations has presented the problem of relative movement between the lamp and the lamp holder.

When incandescent lamps were used for illumination in such installations, their relative movement was not a major consideration since the weight and size of the lamps were not appreciable. But when a large, heavy lamp, such as an electric discharge lamp is used, the increased lamp weight and strain of shock forces upon the lamp assembly may cause lamp outage.

This can be caused by two types of lamp motion, relative to the lamp holder. One type is the rotation of the lamp in its lamp holder. If the lamp is rotated sufficiently, the electric contact between the lamp and the fixture is lost and lamp outage will result. The other type of relative movement concerns a change in the coaxial positioning of the lamp in its lamp holder. If the lamp is shifted in the lamp holder there is a high probability of lamp breakage due to a portion of the bulbous envelope striking the periphery of the lamp holder.

Although the lamps are sufiiciently stable to withstand moderate shock and vibration, lamp outage may occur if the forces are unusually violent or prolonged. In these cases the lamp may be in perfect operating condition but the illumination is still lost.

With regard to prolonged-vibration, if a lamp and fixture are installed in a factory where heavy machinery is operating, the continual vibration may cause the lamp simply to unscrew.

The problem of an unusually violent shock is more severe since it may involve lamp breakage. The lamp holder is a structurally stable device and positioned therein is a threaded shell. The shell may move in the lamp holder when the lamp is shaken, thus breaking the envelope. For example, large numbers of electric discharge lamps have been installed in missile bases and when the missile is launched, a force as high as 30 GS may be produced for 6.5 milliseconds. This force may cause the lamp to shift and strike the lamp holder and breakage can result.

This invention contemplates a means to prevent relative movement between the lamp and the lamp holder and it comprises two rigidly connected clamps maintained in frictional engagement with the lamp and lamp holder, respectively. When the lamp, the lamp holder holder and the two rigidly connected clamps are assembled, the lamp cannot become unscrewed or lose coaxial alignment in the lamp holder.

The principal object of this invention is to prevent relative movement between the lamp, the lamp holder and its shell.

Another object of this invention is to secure an electric discharge lamp rigidly to its lamp holder.

An advantage of this invention is that the lamp and lamp holder may be easily disassembled for replacement of the lamp.

A further advantage of this invention is that the problems of lamp rotation in the holder and lamp breakage due to shock are substantially eliminated.

An advantage of this invention is the inexpensiveness of the stabilizing device and the ease of fabrication.

Other objects, features and advantages of this invention will become apparent to those skilled in the art upon reading the following specification, together with the accompanying drawing.

The FIGURE is a plan view of a high pressure discharge device in its fixture and showing the stabilizing support member according to the invention attached at one end to a lamp holder and at the other end to a mercury vapor lamp. Certain portions are cut away to show the invention in more detail.

As will be seen in the drawing, the high pressure mercury vapor lamp 1 comprises an outer vitreous envelope or jacket 2 of generally tubular form having a central bulbous portion 3. The jacket is provided at its lower end with a re-entrant stem having a press through which extend relatively stiff lead-in wires 6 and 7 connected at their outer ends to the contacts of the usual screw-type base 8 having threads 9. The usual insulated center con tact is provided, although not shown herein.

The neck portion 52 of the lamp is shouldered at its lower end to a portion of its original diameter. When the lamp 1 is screwed in the lamp holder 42, the shoulder is quite near the peripheral edge 55. A slight displacement of threaded shell 51 from the generally coaxial positioning in the fixture will cause the shoulder to strike the peripheral edge 55 and increase the probability of lamp envelope breakage.

The inner arc tube 12 is made of quartz and has sealed therein at opposite ends the main discharge electrodes 13 and 14 which are supported on lead-in wires that constitute the arc tube terminals. Each main electrode com'- prises a core portion which may be a prolongation of the inner end of the lead-in made of a suitable refractory metal such as tungsten or molybdenum. The lead-in is surrounded by a tungsten wire helix. A small elongated piece or sliver of thorium metal (not shown) is inserted between the core and the helix and serves to reduce the cathode drop during operation. An auxiliary starting electrode 18 is provided at the base end of the arc tube adjacent main electrode 13 and comprises the inwardly projecting end of the lead-in wire.

Current lead-in wires have their ends welded to intermediate foil sections of molybdenum which are hermetically sealed within quartz pinch seal portions 21, 22. The foil sections are very thin, for instance approximately .0008 thick and go into tension when the quartz cools without rupturing or scaling off from the quartz. Relatively short molybdenum wire sections 23, 24, 30 are welded to the outer ends of the foil.

Lead-in Wire 30 is connected to the resistor 26. The resistor may have a value for instance of 40,000 ohms and serves to limit current to auxiliary electrode 18 during normal operation of the lamp. Lead-in wire 24 is connected to one portion of the support Wire 59 by the flexible wire 28, whereby the main electrode will be energized.

Lead-in wire 23 is provided for main electrode 13 at the stem or base end of the arc tube. The pinched or flattened end portions 20 and 22 of the arc tube form wide seals using substantially the full diameter of the tube. They are made by flattening or compressing the ends of the arc tube while it is heated. The arc tube is provided with a filling of an ionizable media comprising a supply of mercury in sufficient quantity to be completely vaporized with a pressure in the order of one half to several atmospheres during operation of the lamp. In addition, a small quantity of a rare gas such as argon at a nominal pressure of 25 millimeters of mercury is introduced to facilitate starting.

The internal supporting assembly for the arc tube serves to position the tube susbtantially co-axial within the envelope and to provide a rugged internal support. The lead-in wire 6 is welded to the base 53 of the U- shaped support wire 54. Collars 56 and 57 which hold the arc tube 12 at the pinched portions 20 and 22 are fixedly attached to the U-shaped support wire 54 and thus support the arc tube 12 within the outer envelope 1. A rod 59* bridges the free ends of the U-shaped support wire 54 and is fixedly attached thereto to impart stability to the structure. The free ends of the U-shaped support wire 54 are also provided with a pair of resilient metal leaf springs 60, frictionally engaging the upper tubular portion of the lamp envelope 2. The heat shield 61 is positioned beneath the arc tube 12 and above the resistor 26 so as to protect the resistor from the heat of the arc tube.

The lamp is screwed into the lamp holder 40 in the usual manner. The instant invention eliminates the need of any change in the basic design of screw threaded shell 51 or in the lamp holder 40. Thus even fixtures now in service may be adapted according to this invention and, as is seen, the conventional shell 51 is positioned within conventional lamp holder 40.

The rigidly connected, resilient clamps 41 and 44 serve to inhibit relative movement between the lamp holder 40 and the lamp 1. In the preferred embodiment the clamp 44 extends around the lamp and is held rigidly in place by the mutual coaction of bored flanges 45, 46, and nut and bolt 47. As shown in the cut-away portions, attached on the inner surface of clamp 44 is a layer of resilient, heat resistant tape 48, such as asbestos or woven glass which forms a frictional engagement means. Not only does this tape aid the mechanical grasping ability of the clamp but it also prevents contact of the glass and heat differentials between metal and glass. Furthermore, the friction tape will act as a damper to absorb shock. It is generally quite essential'that the tape overlaps or is slightly wider than the clamp to prevent contact of any portion of the metal and glass.

The resilient clamp 41 is constructed in the same manner as clamp 44 and here, too, tape is. generally used to improve the frictional contact. The nut and bolt 48, placed in the bore of flanges 49 and 50 holds the ends of the clamp 41 securely together.

It is to be noted that clamps 41 and 44, fiting about the socket 42 and neck portion of the bulb 52 respectively, should have a length less than the circumference of the respective supported structures; however, it should have sufficient length so that the flanges 46, 47, 48 and 50 may be joined by suitable attaching means.

Three struts 56 are spot welded between each of the resilient clamps 44 and 41. Although welding is preferred, all of the members forming the stabilizing support 43 may be stamped from a single sheet of metal and appropriately shaped so as. to encircle the lamp and socket. Although three struts are shown, it is apparent that more may be used to impart additional structural stability. It is essential, however, that sufficient free space is provided so that the lamp will be adequately ventilated.

It is apparent that other modifications may be made in the instant invention without departing from the spirit and scope thereof. For example, although nuts and bolts are shown and preferred to engage the ends of the clamps since they are easy to install and relatively cheap, other suitable means may be utilized. While the invention has been described with reference to a mercury vapor lamp, it is apparent that it has applicability to other lamps of double wall construction.

As my invention I claim:

1. In combination with an electric discharge lamp hav-- ing a vitreous outer jacket comprising a bulbous portion and a neck portion, an arc tube disposed within said jacket and an electrical terminal positioned at an end of said lamp, the improved mounting structure which comprises; a lamp holder having a mating threaded shell therein, adapted to hold and be in electrical contact with said terminal of said lamp, means for inhibiting relative movement between said lamp and said holder comprising, a first resilient clamp about said lamp holder, a second resilient clamp about the neck portion of said lamp, means for rigidly aflixing each of said clamps to the lamp neck and holder respectively, means for rigidly connecting said first clamp to said second clamp, frictional engagement means interposed between each of said clamps and said lamp holder and neck portion.

2. In combination with an electric discharge lamp having a vitreous outer jacket comprising a bulbous portion and a neck portion, an arc tube disposed within said jacket and an electrical terminal positioned at an end of said lamp, the improved mounting structure which comprises; a lamp holder having a mating threaded shell therein, adapted to hold and be in electrical contact with said terminal of said lamp, means for inhibiting relative movement between said lamp and said lamp holder comprising, a first resilient clamp about said lamp holder, means for joining the ends of said first clamp to each other, a second resilient clamp about the neck portion of said lamp, means for joining the ends of said second clamp to each other, means for securing said first clamp to said second clamp, frictional engagement means interposed between each of said clamps and said lamp holder and neck portion.

3. In combination with an electric discharge lamp having a vitreous outer jacket, an arc tube disposed within said jacket and an electrical terminal positioned at an end of said lamp, the improved mounting structure which comprises; a lamp holder having a mating threaded shell therein, adapted to hold and be in electrical contact with said terminal of said lamp, means for inhibiting relative movement between said lamp and said lamp holder comprising, a first resilient clamp having attached ends positioned about said lamp holder and in relatively tight frictional engagement therewith, a second resilient clamp having attached ends positioned about said neck portion and in relatively tight frictional engagement therewith, means for attaching said first clamp to said second clamp.

4. In combination with an electric discharge lamp having a vitreous outer jacket, an arc tube disposed within said jacket and an electrical terminal positioned at an end of said lamp, the improved mounting structure which comprises; a lamp holder having a threaded shell there in adapted to hold and be in electrical contact with said terminal of said lamp, means for inhibiting relative movement between said lamp and said lamp holder comprising, a first resilient clamp about said lamp holder, means for joining the ends of said first clamp to each other,

a second resilient clamp about the neck portion of said lamp, means for joining the ends of said second clamp to each other, means for rigidly connecting said first clamp to said second clamp, frictional engagement means comprising strips of tape between said clamps and said lamp and lamp holder respectively.

5. In combination with an electric discharge lamp having a vitreous outer jacket, an arc tube disposed within said jacket and an electrical terminal positioned at an end of said lamp, the improved mounting structure which comprises; a lamp holder having a threaded shell therein adapted to hold and be in electrical contact with said terminal of said lamp, means for inhibiting the relative movement between said lamp and said lamp holder comprising, a first resilient clamp about said lamp holder,

means for joining the ends of said first clamp to each other, a second resilient clamp about the neck portion of said lamp, means for joining the ends of said second clamp to each other, means for rigidly connecting said first clamp to said second clamp, frictional engagement means comprising strips of tape on the inner surface of each of said clamps, each of said strips of asbestos tape being wider than each of the respective clamps.

Betts June 29, 1948 Lamb Oct. 28, 1952 

